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1. Field the Invention
The present invention relates to the testing of railroad locomotive wheels and railroad car wheels for flaws such as cracks and the like. A hand held wand with a yoke end portion that carries a transducer pivotally attached to the yoke at its lower or distal end portion can be used to maintain a flat transducer wear surface selected in continuous face-to-face contact with the selected inside or outside surface of the wheel, even when the locomotive is attached to a string of other locomotives or cars so that movement of the locomotive wheels for testing purposes is difficult or at least very expensive.
2. General Background of the Invention
Locomotives are often connected together, one after the other in order to pull very heavy loads. These locomotives are very expensive pieces of equipment that are used on an almost continual basis in order to maximize the return to their owner. As with any mechanical vehicle, locomotives continuously wear and the locomotive wheels are no exception.
The wheels of locomotives are subjected to substantial wear because they bear directly against metal rails. After wear removes a certain amount of the wheel, the wheel must be replaced. In order to test these locomotive wheels on a regular basis for flaws and excess wear, ultrasonic testing has been employed. In the prior art, ultrasonic testing has typically used a round transducer that is hand held by a technician to position a wear surface against the surface of the railroad wheel to be tested. The transducer is moved continuously back and forth while the technician observes an oscilloscope to look for peaks of a graphical output that equates with a flaw or defect in the wheel.
One of the problems with this type of prior art ultrasonic testing of railroad locomotive wheels is that of lost time and extra expense because the locomotive must be moved. Typically, a locomotive will be tested by locating the locomotive above a work pit so that the technician can place the transducer against the desired surface of the wheel and move the transducer back and forth in a circuitous path until about one-half of the peripheral surface of the wheel has been tested. The technician typically uses chalk marks on the surface of the wheel to mark off an area that equates with about 180 degrees or one-half of the wheel. After one-half of the wheel is tested, the locomotive must then be moved so that the second half of the wheel is presented to the technician.
The unscheduled movement of a railroad locomotive can be a very expensive proposition. Often times, a locomotive is attached to a long string of other locomotives and/or railroad cars and cannot simply be rolled or moved without involving a number of personnel that must be paid, sometimes on an overtime basis. When a potential problem (e.g., excessive wear) is suspected, testing must be conducted immediately to avoid an accident, derailing, personal injury and possible fatalities.
Thus, there is a need for a method of testing railroad locomotive wheels wherein testing can be achieved without having to roll the locomotive.
Incorporated herein by reference is the xe2x80x9cAssociation of American Railroadsxe2x80x94Operations and Maintenance Departmentxe2x80x94Mechanical Divisionxe2x80x94Manual of Standards and Recommended Practicesxe2x80x94Section Gxe2x80x94Wheels and Axlesxe2x80x94Issue of 1994xe2x80x9d published by the Association of American Railroads, 50 F Street, N.W., Washington, D.C. 20001-1564.
It is thus an object of the present invention to provide a simple, straightforward, yet workable solution to the problem of testing a railroad locomotive wheel without having to move the locomotive in order to present various portions of the wheel to the technician that is testing the wheel for defects.
The present invention solves these problems in a simple, straightforward, yet efficient manner by providing a probe apparatus and method of testing that includes an elongated handle having a lower or distal end portion that forms a pivotal connection with a transducer.
The transducer presents a flat wear surface that directly contacts the wheel during testing. One of the features of the present invention is that two handles are provided, a short handle for testing the outside of the wheel and a longer handle for testing the inside of the wheel. This enables the technician to apply very even pressure which is critical during testing of railroad wheels using an ultrasonic transducer.
The present invention thus provides an improved method of testing a metallic railroad wheel having a hub, web, wear surface, and a thickened peripheral portion with inner and outer surfaces.
The method of the present invention first defines inner and outer surfaces that are test surfaces on the respective inner and outer surfaces of the thickened peripheral portion of the wheel.
The user then places a transducer with a flat wear surface on the inner surface test area. A transducer is manipulated with an elongated handle having a gripping portion that can be gripped by a technician during use and a digital end portion that is pivotally connected to the transducer.
By varying the angle between the plane of the wear surface and the axis of the handle at the gripping surface, a very efficient testing pattern can be developed by the user and while simultaneously maintaining appropriate flat surface to surface contact between the wear surface of the transducer and the test surface in question.
An oscilloscope is used to display defects that may exist in the wheel at the inner surface test area.
The method of the present invention further comprises the step of applying a liquid to the transducer wear surface so that the liquid is continuously applied to the wheel during testing for acoustic coupling and for indicating the part of the wheel that has been tested already. A fluid source can be channeled to the transducer for continuously supplying fluid to the transducer so that as the user moves the transducer over the test surface area, the portion of the test surface area that has been tested is continuously wetted for clearly indicating to the user that portion of the wheels has already been tested.
The method of the present invention comprises varying the angle by pivoting the handle upon the transducer.
With the testing of the present invention, the further step is provided of using two handles of different lengths for testing the respective inside and outside surfaces of the wheel. This enables the user to access portions of the wheel that is typically inaccesible because of parts of the train chassis that extend downwardly toward the middle of the wheel.
The method of the present invention further comprises the step of attaching the probe to the handle with two spaced apart pivot pins.
The method of the present invention further comprises the step of placing the pivot pins about one hundred eighty degrees (180xc2x0) apart.
With the method of the present invention, the handle has a distal end portion with a slot surrounded by a wall portion and further comprises the steps of mounting the transducer within the slot and pivoting the transducer relative to the handle with pins that extend between the wall portion and the transducer.